If I recall correctly that was keeping your computer from booting up. The display dimming out over time but the voltages being OK is an odd one. The contrast input to the LCD is on pin 4, labeled VR1. If that voltage does not lower as the display grows dim, then I might suspect the LCD unit itself.
The LCD is built like the Model 100. The contrast voltage input is used to create v2, v3, v4, v5, v6 ON THE lcd. Those can be checked to see if they change as LCD dims. One of the HD 44103 driver chips might be going bad as well. Jeff Birt From: M100 <m100-boun...@lists.bitchin100.com> On Behalf Of Robert J. Hutchins Sent: Wednesday, May 5, 2021 4:04 PM To: m...@bitchin100.com Subject: Re: [M100] NEC PC-8201(A) Recapping Help Jeff, Maybe it has the problem that you fixed on mine? The bad buffer chip? Robert From: M100 [mailto:m100-boun...@lists.bitchin100.com] On Behalf Of ExPLIT | Pawel Radomychelski Sent: Wednesday, May 05, 2021 1:28 PM To: m...@bitchin100.com <mailto:m...@bitchin100.com> Subject: Re: [M100] NEC PC-8201(A) Recapping Help Thanks for the Info, Jeff. No, i have no leaking caps on my PC-8201, but i think something is wrong with couple of my units. Sometimes, they switched, sometimes display became unreadable, sometimes contrast can't be changed. +5 and -5 are ok, so maybe some of the chips need to be replaced... -- Kind regards / Mit freundlichen Grüßen ExPLIT IT Solutions Pawel Radomychelski -----Original Message----- From: Jeffrey Birt <bir...@soigeneris.com <mailto:jeffrey%20birt%20%3cbir...@soigeneris.com%3e> > Reply-To: m...@bitchin100.com <mailto:m...@bitchin100.com> To: m...@bitchin100.com <mailto:m...@bitchin100.com> Subject: Re: [M100] NEC PC-8201(A) Recapping Help Date: Wed, 5 May 2021 14:38:42 -0500 I have only worked on a few PC-8201/A computers. I have not seen one that needed recapped. The TRS-80 Model 100 and Olivetti M10 are a different story, they all need recapped. Do your capacitors appear to be leaking or do you suspect they are faulty? Jeff Birt From: M100 <m100-boun...@lists.bitchin100.com <mailto:m100-boun...@lists.bitchin100.com> > On Behalf Of ExPLIT | Pawel Radomychelski Sent: Wednesday, May 5, 2021 7:06 AM To: m...@bitchin100.com <mailto:m...@bitchin100.com> Subject: [M100] NEC PC-8201(A) Recapping Help Hello Friends! Have someone already did a recapping job on the NEC PC-8201 or PC-8201A ? I am searching for a starting point, or simple table sheet which capacitors / voltage / capacity should be used ? Any help is welcome. Thanks -- Kind regards / Mit freundlichen Grüßen ExPLIT IT Solutions Pawel Radomychelski
